CVE-2020-0688: Microsoft Exchange Server Validation Key Remote Code Execution Vulnerability

Vulnerability summary

CVE-2020-0688 is a high (CVSS 9.0) Improper Authentication vulnerability in Microsoft Exchange Server. It is known to be exploited: CISA lists it, first on 03-11-2021. It has been used in ransomware campaigns. EPSS estimates a 99.96% chance of exploitation in the next 30 days, higher than 99.9% of scored vulnerabilities. 5 public exploits are recorded.

Timeline

1. 11-02-2020
   PublishedVulnerability first disclosed.
2. 03-11-2021
   Added to CISA KEVMicrosoft Exchange Server Validation Key Remote Code Execution Vulnerability
3. 03-05-2022
   CISA remediation dueApply updates per vendor instructions.
4. 21-10-2025
   Last modifiedVulnerability information updated.

Description

A remote code execution vulnerability exists in Microsoft Exchange software when the software fails to properly handle objects in memory, aka 'Microsoft Exchange Memory Corruption Vulnerability'.

• CWE-287Improper AuthenticationWhen an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.